1. Field of the Invention
The present invention relates to a method and a device for characterizing or analyzing the water flowing in the primary circuit of a nuclear reactor (e.g. a boiling water reactor).
During operation of a nuclear reactor, corrosion products appear in the water in the primary circuit. The primary circuit in a boiling water reactor leads steam generated in the reactor vessel to a steam turbine, and from there to a condenser. Condensate formed in the condenser, after preheating, is returned to the reactor vessel. The primary circuit is a pressurized water reactor leads water heated in the reactor vessel to a steam generator and from there to the reactor vessel. For the most part, the corrosion products generated in the primary circuit of the reactor consist of oxides containing one or more metals of the kinds which are included in the construction of the primary circuit which is mainly iron, but further includes among other things, nickel, cobalt, chromium, manganese, titanium, molybdenum, zinc and zirconium. The corrosion products, which for the most part occur in a colloidal state, become radioactive due to the neutron flux in the reactor core. The concentration of these corrosion products in the water is extremely low, of the order of magnitude of ppb, that is, of the order of magnitude of 10.sup.-9 parts by weight per part by weight of water.
The amount of, and the type of, the corrosion products present are also affected by the temperature, particularly by the pH of the water and by the concentration of hydrogen and of oxygen dissolved in the water. The corrosion products are therefore indicators of important properties of the reactor water.
By examining the corrosion products in the reactor water, important conclusions can be drawn, among other things, concerning the pH of the reactor water, the degree of radioactive contamination in the primary circuit of the reactor and the degree of oxide growth in fuel tubes and channels of Zircaloy.
2. Description of the Prior Art
In previously known methods of analyzing water samples from nuclear reactors for characterizing the water-chemical conditions in the reactor, the water has been cooled down to room temperature in special sampling systems, and physical, chemical and radioactive properties in the cooled water have then been determined. The results of analyses according to these methods are, in most respects, not representative of the conditions actually prevailing inside the reactor at its operating temperature when the solubilities and equilibrium conditions are quite different from those existing at room temperature.